This is known to cisco. The ACS 5.2 guide does talk about the same.
"ACS Monitoring & Reports Viewer logs are limited to 100 pages. ACS applies filters like Last 30 days only on the top 100 pages. In case of very heavy load ACS Monitoring & Reports Viewer may not be able to display full information for filters like Last 30 days. During critical period, it is recommended that you export the data to a CSV file after generating report for each one or two hours."
User Guide:
http://www.cisco.com/en/US/partner/docs/net_mgmt/cisco_secure_access_control_system/5.2/user/guide/viewer_troubleshooting.html#wp1077489
CSCtq06579 ACSview Reports carry only 100 pages
I guess in ACS 5.5 this limit will be 500 pages.
As of now you may go through the below listed link:
https://supportforums.cisco.com/docs/DOC-28117
~BR
Jatin Katyal
**Do rate helpful posts**
~Jatin
